Azizan Abu Samah

The Occurrence of Haze in Malaysia: A Case Study in an Urban Industrial Area

Abstract — Klang Valley, a heavily industrialized urban area in Malaysia, has experienced severe haze episodes since the early 1980s. Total Suspended Particulate matter (TSP) is used in studying this phenomenon. Three severe haze episodes during the early 1990s are reviewed; August 1990, October 1991, and August–October 1994. The nature of these episodes, their possible causes, and their major features are discussed. Meteorological conditions associated with these episodes were analyzed. Results of the study indicate that stability and trapping of particles are the main factors affecting the pollution during haze periods. Maximum total suspended matter (TSP) was recorded in October 1991. The August–October 1994 episode was the most persistent and least affected by meteorological variables. Analysis of wind direction data showed that southerly and southwesterly winds coincided with the worst haze periods.

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: Coastal processes, land-use change and air quality

We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NOx emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.

Dynamics of the Water Circulations in the Southern South China Sea and Its Seasonal Transports.

A three-dimensional Regional Ocean Modeling System is used to study the seasonal water circulations and transports of the Southern South China Sea. The simulated seasonal water circulations and estimated transports show consistency with observations, e.g., satellite altimeter data set and re-analysis data of the Simple Ocean Data Assimilation. It is found that the seasonal water circulations are mainly driven by the monsoonal wind stress and influenced by the water outflow/inflow and associated currents of the entire South China Sea. The intrusion of the strong current along the East Coast of Peninsular Malaysia and the eddies at different depths in all seasons are due to the conservation of the potential vorticity as the depth increases. Results show that the water circulation patterns in the northern part of the East Coast of Peninsular Malaysia are generally dominated by the geostrophic currents while those in the southern areas are due solely to the wind stress because of negligible Coriolis force there. This study clearly shows that individual surface freshwater flux (evaporation minus precipitation) controls the sea salinity balance in the Southern South China Sea thermohaline circulations. Analysis of climatological data from a high resolution Regional Ocean Modeling System reveals that the complex bathymetry is important not only for water exchange through the Southern South China Sea but also in regulating various transports across the main passages in the Southern South China Sea, namely the Sunda Shelf and the Strait of Malacca. Apart from the above, in comparision with the dynamics of the Sunda Shelf, the Strait of Malacca reflects an equally significant role in the annual transports into the Andaman Sea.

The application of the Water Erosion Prediction Project (WEPP) model for the estimation of runoff and sediment on a monthly time resolution

The Water Erosion Prediction Project (WEPP) model is utilized to simulate the sediment and runoff processes. According to previous studies, WEPP model provides impressive results in watersheds of diverse climates and scales. It is also capable of modeling the sediment transportation processes and consequently predicting subsequent deposition sites. In this study, the geo-spatial interface for WEPP (GeoWEPP) was employed as a GIS framework to extract the data required from the ASTER Global Digital Elevation Model (ASTER-GDEM) dataset which was subsequently used as the model input. The case study was based on monthly data consisting of average sediment and runoff estimation from the Emameh sub-basin, in northern Iran. The model estimations were validated through field measurements. Two statistical measures of co-efficiency including the Nash–Sutcliffe Efficiency (NSE), and the coefficient of determination (R2) were considered to evaluate how well the model predictions could explain the variability of observations in the field. The model performed favorably as corroborated by a reasonably high NSE of 0.99 and an R2 value of 0.92 for sediment. In the case of runoff, the results were slightly inferior, but still acceptable with an NSE of 0.76 and R2 value of 0.62.

Extreme Rainstorms that Caused Devastating Flooding across the East Coast of Peninsular Malaysia during November and December 2014

AbstractDuring the early boreal winter (northeast) monsoon (November–December), cold air frequently bursts out from intense Siberian highs toward the Chinese coast in response to the development and movement of a 500-hPa trough. The resultant strong low-level northwesterlies turn into northeasterlies across the South China Sea as “cold surges.” On interacting with the near-equatorial trough, mesoscale convective systems form north of the trough, normally giving rise to heavy downpours and severe flooding, mainly along the coastal stretch in the east coast states of Peninsular Malaysia. In November 2014, a 1-week-long episode of heavy downpours, producing more than 800 mm of rain, occurred along the coastal stretch of northeastern Peninsular Malaysia. However, during December 2014, two episodes of extreme rainfall occurred mostly over inland and mountainous areas of the east coast of Peninsular Malaysia, in particular across its northern sector. These two unusual events, which lasted a total of 11 days and...

Bacterial community composition in Adélie (Pygoscelis adeliae) and Chinstrap (Pygoscelis antarctica) Penguin stomach contents from Signy Island, South Orkney Islands

Penguin stomach microbiota and its variability are important as these microbes may contribute to the fitness of the host birds and their chicks, and influence the microbial ecosystem of the surrounding soils. However, there is relatively little knowledge in this area, with the majority of studies focused on their deposited faeces. Here we investigated whether similar foraging strategies in adjacent colonies of different penguin species lead to similar temporarily conserved stomach microbiota. To do this, we studied the inter- and intra-specific variations in bacterial community composition in the stomach contents of sympatrically breeding Adélie (Pygoscelis adeliae) and Chinstrap (Pygoscelis antarctica) Penguins, which consumed a diet of 100% Antarctic krill (Euphausia superba) under a similar foraging regime on Signy Island (maritime Antarctic), using a high-throughput DNA sequencing approach. Our data show that Adélie and Chinstrap Penguins shared 23–63% similarity in the stomach bacterial community composition, with no significant differences observed in the α-diversity or the assemblages of frequently encountered groups of operational taxonomic units (OTUs). The most frequently encountered OTUs that were shared between the species represented members of the phyla Fusobacteria, Firmicutes, Tenericutes and Proteobacteria. OTUs which were unique to individual birds and to single species formed approximately half of the communities identified, suggesting that stomach microbiota variability can occur in penguins that forage and breed under similar environmental conditions.

A Strong Wind Event on the Ross Ice Shelf, Antarctica: A Case Study of Scale Interactions

AbstractIn situ observations, satellite imagery, numerical weather prediction, and reanalysis fields are used to investigate the synoptic and mesoscale environment of a strong wind event (SWE) at McMurdo Station/Ross Island region on the Ross Ice Shelf, Antarctica, on 10 October 2003. The SWE occurred during the passage of a sequence of three mesoscale low pressure systems from the central Ross Ice Shelf to the southwest Ross Sea. A potential vorticity (PV) analysis showed that the lows drew air of continental origin down the glacial valleys of the Transantarctic Mountains and onto the ice shelf as a katabatic drainage flow. However, the analysis indicated that the air mass associated with the SWE was of recurved maritime origin drawn in by the second mesoscale low (L2). This air mass approached McMurdo Station from the south where interactions with the orography played a critical role. In the early stages of the event, when the wind speed was less than 10 m s−1, the air was deflected around the topograph...

Precipitation instruments at Rothera Station, Antarctic Peninsula: a comparative study

ABSTRACT Direct measurement of precipitation in the Antarctic using ground-based instruments is important to validate the results from climate models, reanalyses and satellite observations. Quantifying precipitation in Antarctica faces many unique challenges such as wind and other technical difficulties due to the harsh environment. This study compares a variety of precipitation measurements in Antarctica, including satellite data and reanalysis fields atRothera Station, Antarctica Peninsula. The tipping bucket gauges (TBGs) were less sensitive than laser-based sensors (LBSs). The most sensitive LBS (Visibility and Present Weather Sensor, VPF-730) registered 276 precipitation days, while the most sensitive TBG (Universal Precipitation Gauge, UPG-1000) detected 152 precipitation days. Case studies of the precipitation and seasonal accumulation results show the VPF-730 to be the most reliable precipitation sensor of the evaluated instruments. The precipitation amounts given by the reanalyses were positively correlated with wind speed. The precipitation from the Japanese 55-year Reanalysis was most affected by wind speed. Case studies also show that during low wind periods, precipitation measurements from the instruments were very close to the precipitation measurement given by the Global Precipitation Climatology Project (GPCP) 1-degree-daily (1DD) data. During strong wind events, the GPCP 1DD did not fully capture the effect of wind, accounting for the relatively small precipitation amount. The Laser Precipitation Monitor (LPM) and Campbell Scientific-700 (CS700H) experienced instrumental errors during the study, which caused the precipitation readings to become exceedingly high and low, respectively. Installing multiple LBSs in different locations (in close proximity) can help identify inconsistency in the readings.

Links between bacteria derived from penguin guts and deposited guano and the surrounding soil microbiota

Penguins are an important indicator of marine ecosystem health and a major contributor of nutrients to terrestrial ecosystems in Antarctica. Their stomach microbiota is influenced by both the prey consumed and their foraging environment in the sea. As penguins feed at sea and breed on land, they might be expected to transfer microbes (e.g. prey-associated and marine bacteria) as well as nutrients from their stomachs while regurgitating food or in their guano to the surrounding terrestrial environment. However, most research attention to date has focused separately on the penguin gut microbiota (via cloacal/guano samples) and the terrestrial soil microbiota, and any relationship between them has yet to be established. Here, we analysed the bacterial communities in stomach regurgitates and cloacal swabs from the same individual birds, freshly deposited guano and rookery soils of two Pygoscelis penguins that breed sympatrically on Signy Island (South Orkney Islands, maritime Antarctic) using a high-throughput DNA sequencing method. Our data do not support the hypothesis that bacteria transferred from penguin guts and/or deposited guano make a significant contribution to the communities of the surrounding terrestrial microbial ecosystem. In both penguin species, composition of bacterial communities differed between the four sample types, with Jaccard similarities ranging between 10 and 36%. Assemblages of the dominant and co-occurring bacterial communities in rookery soils were either significantly negatively correlated or not correlated with the three other sample types. Sample-specific communities were also identified in this study, contributing around 63% of the identified diversity overall.

Validation of TRMM 3B42 V6 for estimation of mean annual rainfall over ungauged area in semiarid climate

This research compares data from the Tropical Rainfall Measuring Mission 3B42 V6 with data obtained from 19 synoptic rain gauges during the period 1998–2010 over the semiarid climate of Khorasan Razavi, Iran. Validation was performed using three spatial extents, including 1 TRMM grid face from the synoptic station (1PTRM), 3 TRMM points surrounding the synoptic station (3PTRM) and 5 TRMM points surrounding the synoptic station (5PTRM), using ArcGIS 10.2 software. The perfect and poor r were obtained at stations S08 and S19, with values of 0.92 and 0.26, respectively. According to the Nash–Sutcliffe efficiency coefficient, the TRMM satellite can predict the spatial variation of the mean annual rainfall by 0.23, 0.43 and 0.38 for 1PTRM, 3PTRM and 5PTRM, respectively, at 19 stations. The agreement significantly increases by 0.88, 0.83 and 0.80 for 1PTRM, 3PTRM and 5PTRM, respectively, when gauges S05, S07, S11 and S13 are excluded from the dataset, which may be associated with orographic or instrumental error at the stations.